The apparent relation of microbial dextran formation and the formation of dental caries suggests that a thorough investigation of the mode of formation should be made. Dextran sucrase catalyzes the synthesis of dextran from sucrose and studies on its nature will be continued. A study of the nature of the two or more enzymes shown to be responsible for the entire synthesis of dextran will be made, along with the purification of the enzymes. The mechanisms of the enzymes have been studied, and more definitive evidence will be sought to establish the mode of catalysis, and the active site amino acids. Questions relating to mechanism will be examined also; e.g., whether the enzyme acts in a multichain or a single chain manner, whether chain growth occurs at the reducing or the nonreducing ends of chains.